docs: Expand SIG meeting welcoming language (#4552)

Author: cijothomas

README.md

@@ -108,6 +108,8 @@ We meet weekly on Thursday at 9AM PT. The meeting is subject to change depending
 
 Meeting notes are available as a public [Google doc](https://docs.google.com/document/d/18w8zOBm_mbety0OqlPwxc7dvnfu641EgmrO4AdJef0U/edit?tab=t.0).
 
+The meeting is open for all to join. We invite everyone to join our meeting, regardless of your experience level. Whether you're a seasoned OpenTelemetry developer, just starting your journey, or simply curious about the work we do, you're more than welcome to participate!
+
 ### Maintainers
 
 - [Aaron Abbott](https://github.com/aabmass), Google